Commit 26949bac authored by Wedson Almeida Filho's avatar Wedson Almeida Filho Committed by Miguel Ojeda
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rust: types: implement `ForeignOwnable` for `Box<T>` 



This allows us to hand ownership of Rust dynamically allocated
objects to the C side of the kernel.

Signed-off-by: default avatarWedson Almeida Filho <wedsonaf@gmail.com>
Reviewed-by: default avatarGary Guo <gary@garyguo.net>
Reviewed-by: default avatarVincenzo Palazzo <vincenzopalazzodev@gmail.com>
Reviewed-by: default avatarAlice Ferrazzi <alice.ferrazzi@miraclelinux.com>
Reviewed-by: default avatarAndreas Hindborg <a.hindborg@samsung.com>
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 0fc4424d

rust/kernel/types.rs

+23 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 


//! Kernel types.



use alloc::boxed::Box;

use core::{

    cell::UnsafeCell,

    mem::MaybeUninit,
@@ -62,6 +63,28 @@ unsafe fn borrow_mut(ptr: *const core::ffi::c_void) -> ScopeGuard<Self, fn(Self) 
    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self;

}



impl<T: 'static> ForeignOwnable for Box<T> {

    type Borrowed<'a> = &'a T;



    fn into_foreign(self) -> *const core::ffi::c_void {

        Box::into_raw(self) as _

    }



    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {

        // SAFETY: The safety requirements for this function ensure that the object is still alive,

        // so it is safe to dereference the raw pointer.

        // The safety requirements of `from_foreign` also ensure that the object remains alive for

        // the lifetime of the returned value.

        unsafe { &*ptr.cast() }

    }



    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {

        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous

        // call to `Self::into_foreign`.

        unsafe { Box::from_raw(ptr as _) }

    }

}



/// Runs a cleanup function/closure when dropped.

///

/// The [`ScopeGuard::dismiss`] function prevents the cleanup function from running.